The anterior chamber paracentesis is in a technical field where the aqueous humor flows from eyes into the anterior chamber by puncturing the cornea, it has an important utilization value in the ophthalmic clinical scientific research work and is mainly used in the following three aspects: (1) lowering the intraocular pressure; (2) collecting the aqueous humor; (3) other therapeutic anterior chamber drainage.
Firstly, the anterior chamber paracentesis can lower the intraocular pressure, it can be applied to the following circumstances: a treatment for transient lowering of the intraocular pressure of the angle-closure glaucoma, the open-angle glaucoma, the secondary glaucoma and some other diseases of the ocular hypertension; a adjuvant therapy of the glaucoma trabeculectomy; the acute central retinal artery occlusion and so on. Theoretically, it will cause acute anterior optic nerve ischemia or central retinal vein occlusion when the intraocular pressure is greater than 40 mmHg, if the intraocular pressure is greater than 70 mmHg for several minutes, it will cause central retinal artery atrophy and occlusion, if the intraocular pressure cannot be controlled in time, it will cause dramatic decline in visual function and vision loss even worse. Therefore, when the intraocular pressure is particularly high or sudden rising, the anterior chamber paracentesis can lower the intraocular pressure effectively in a short time to protect visual function and create an opportunity for the further treatment. The anterior chamber paracentesis can also be used to reduce severe complications resulted from the sudden lower of the intraocular pressure during the glaucoma trabeculectomy. As to acute central retinal artery occlusion, the anterior chamber paracentesis can improve the perfusion of the retina and make the arterial embolus rush to the distal by the blood flow sometimes.
Secondly, it has important implications for the diagnosis of some eye diseases to test the aqueous humor collected by the anterior chamber paracentesis. For instance, it has an important guiding significance in collecting the aqueous humor to test pathogenic culture, cytology, pthogenic DNA etc. so as to identify the infectious and non-infectious uveitis and masquerade syndrome. Furthermore, it can also be utilized in various forms of scientific research by collecting the aqueous humor.
Finally, the anterior chamber paracentesis can also be applied to the treatment of the anterior chamber drainage under the circumstance of the chemical alkali burn in eyes, the hyphema and so on.
However, there are no unified special equipments and supplies for the implementation of the anterior chamber paracentesis at present, people use a 1 ml syringe as the anterior chamber Paracentesis syringe and use a 1 ml syringe to collect the aqueous humor in the clinical practice, it has several problems as: (1) because there is no fixed support during the puncture, the 1 ml needle lacks stability in the anterior chamber and the operator needs to control the depth of the needle insertion on his own, it is easy for the novice to damage the cornea, iris, crystalline lens or any other adjacent tissues; (2) the outflow of the aqueous humor cannot be precisely controlled. If a 1 ml syringe punctures the anterior chamber in a high intraocular pressure, the aqueous humor outflows very fast due to the large pressure difference between the inside and outside of eyeballs, it causes a sudden drop of the intraocular pressure, rapid shallowing and even loss of the anterior chamber, it may lead to the iris and crystalline lens contacted with the corneal endothelium which causes the damage of the corneal endothelial cells and crystalline lens. The sudden drop of the intraocular pressure also causes some severe complications such as the cyclodialysis, the edema of the ciliary body, the choroidal detachment, explosive suprachoroid cavity hemorrhage and so on; (3) the direct communication between the puncture point and outside increases the intraocular infection; (4) the aqueous humor needs to be transferred to a Eppendorf tube after collection: on one hand, there is some aqueous humor leaving in the needle tube which causes the waste of the sample, the rest of the microsamples may not be enough to accomplish subsequent inspections and research; on the other hand, it increases the risk of the sample pollution in the process of the aqueous humor transferring which may interfere the results of clinical test and research. It may reduce the rate of the endophthalmitis and sample pollution to operate the anterior chamber paracentesis and collect the aqueous humor in an operation room, but it increases a lot of additional process and inconvenience. In regard of the problems above, the anterior chamber paracentesis and the aqueous humor inspection have been greatly limited in the clinical practice at present.
In 2005, Yang Shaoyuan etc. designed an anterior chamber Paracentesis syringe (patent N.O.: 200520125935), the Paracentesis syringe had made an improvement in the needle, it added flanks on both side of the needle to avoid deep puncture, it solved problem (1); in 2010, Li Sizhen etc. designed an anterior chamber Paracentesis syringe (patent N.O.: 2010201582223), it divided the Paracentesis syringe into two identical volume chambers and left a hole on the side which allowed the aqueous humor to outflow slowly, it mainly solved problem (2). To solve the four problems mentioned above comprehensively, the inventor designed a new anterior chamber Paracentesis syringe and expected to provide a safer, more convenient and functional anterior chamber paracentesis tool for the ophthalmic clinical and scientific research.